Water quality requirements are usually determined from the usage of the water. Water can be broadly classified as potable and non-potable. Non-potable water is used mainly for industrial purposes, such as cleaning, production of non-food items and raw materials, utilitarian facilities systems such as cooling towers, boilers and condensers and domestic purposes in fountains, swimming pools and home ponds. Potable water is used mainly for water distribution systems in schools, hospitals and homes.
Three main problems are identified for water and its usages. They are namely fouling, corrosion and bacterial contamination. Generally, when fouling occurs, layers of scale will form. Scaling greatly decreases heat efficiency, increases the chiller pressure and increases the power consumption. It has been reported that there is a 25% increase of electrical consumption when the scale thickness is ⅛ inch. The effects of scale formation in water heating systems are also apparent in homes. Significant cost is incurred for cleaning up these deposits.
Further, scale causes parts such as valves to malfunction and results in leaks. Scaling also creates an oxygen-deprived environment under the deposits which favours growth of anaerobic bacteria, which in turn induces further problems of corrosion. In particular, staining on pipes and facilities such as fountains may be induced.
The second main problem identified is corrosion. Corrosion is the process of metal dissolution, usually by oxidation. It results in substantial material breakdown and premature degradation of system equipment. As a result, the quality of the original material becomes inferior after corrosion. There will be a direct decrease in strength of the materials, reduction in thickness and in certain cases, pit formation. Corrosion also result in serious leaking problems and malfunction of the systems.
The third main problem identified is bacterial contamination. Diverse species of bacteria can be found in both the natural and the human environment. These micro-organisms are able to affect human health to a great extent. Due to the wide diversity of existing bacteria, it is difficult to identify and combat them. Thus, there is a need to control bacteria growth in water to protect human health from being affected. Further, bacteria growth control will help in preventing other bacteria induced problems.
Therefore, water treatment is essential for controlling fouling, corrosion and bacterial contamination. There are various water treatment methods and they may be divided basically into physical and chemical treatment methods. These methods are then further classified according to their techniques based on the requirements of the various purposes of water treatment.
In general, chemical treatment methods require a great amount of maintenance as periodic dosing needs to be carried out and in accurate and controlled amounts for effective control and may use chemicals that are especially harmful to human health, suspected to possess carcinogenic effects, and pose a threat to the environment.
Use of magnetic fields has been suggested to prevent scale formation by using magnetic fields strength to cause molecular changes or solution properties to prevent the bonding of scale-forming particles. For example, permanent magnets have also been used, but were found to cause the formation of soft sludge over the formation of hard scale that tends to cling to the surface. The effect of scale control is greatly limited by such conditions.
Use of electromagnetic fields for water treatment has been suggested. For example, U.S. Pat. No. 438,579 discloses a device which uses electromagnetic fields generated by electromagnets with electric coils positioned at right angles to the conduit on which they are mounted. However, mechanical failure in these devices could cause the cores of the electromagnets to stop rotating.
In U.S. Pat. No. 4,865,748, electromagnetic test signals of varied frequency are initially directed into a fluid filled system at a first location. A treatment frequency, generally the frequency at which maximum absorption is observed, is then selected from such absorption/emission profile and treatment is carried out at such selected fixed frequency.
Irradiation by UV radiation has also been suggested to distort or destroy nucleic acids, however, UV radiation was found not capable of effectively breaking up the biofilm and is costly and harmful to human health.
Other technologies now make use of high power consumption electrohydraulic shock treatment utilising the physical and electrochemical effects of the electrostatic field to disperse bacteria and scale particles to prevent them from forming together. However, bacterial counts cannot be controlled. Also, the only means to help prevent corrosion in such treatments is through the control of biofouling and not directly dealing with corrosion itself.
However, the existing water treatment methods are typically designed to solve a certain particular problem. It should be noted that when one problem is not addressed properly, it could lead to other problems. The existing water treatment methods are inadequate for situations where multiple and interrelated problems arise, such as e.g. in cooling towers.
There is therefore a need for providing an alternative treatment method and system which may address one or more of the above disadvantages.